1. Field of the Invention
The invention relates to optical disc player systems and a method for controlling a decoding unit to read data from a memory device, more particularly to an optical disc player system and a method of controlling a decoding unit in the optical disc player system to read encoded bitstream data from a buffer memory, and an optical disc player system capable of saving the memory bandwidth between a bitstream demultiplexer and a memory.
2. Description of the Prior Art
FIG. 1 illustrates a conventional DVD player system 1 that includes a channel decoder 11 for reading and error-correcting the encoded bitstream data from a disc, a track buffer 13 connected to the channel decoder 11 via a memory interface 15 for storing error-corrected bitstream data from the channel decoder 11, a source decoder 12 connected to the channel decoder 11 for decoding the bitstream data from the channel decoder 11, and a source buffer 14 connected to the source decoder 12 via a memory interface 16 for storing decoded video and audio data from the source decoder 12. In an actual design, the channel decoder 11 and the source decoder 12 are implemented using two separate chips, thereby resulting in a relatively high cost. In order to reduce costs, there is provided a combined chip integrated with the aforesaid functions of the channel and source decoders.
FIG. 2 illustrates another DVD player system 2 that includes a decoding unit 21 having a channel decoder 11′ and a source decoder 12′. The integrated decoding unit 21 performs functions the same as those in the system of FIG. 1, and a combined buffer memory 22 connected to the decoding unit 21 via a memory interface 23. Referring to FIG. 3, the buffer memory 22 includes a track buffer 221 for storing data from a disc, and a bitstream buffer 222 for storing demultiplexed bitstream data processed by a bitstream demultiplexer 24 and decoded video and audio data for playback. The decoding unit 12′ includes an audio decoder 121, a video decoder 122, a sub-picture decoder 123 and a navigation decoder 124. During a decoding procedure, the bitstream demultiplexer 24 reads encoded bitstream data from the track buffer 221 of the buffer memory 221 via the memory interface 23. After error-correcting and demultiplexing of the encoded bitstream data, the demultiplexed bitstream data is transferred to the bitstream buffer 222 of the buffer memory 22 via the memory interface 23. The decoders 121, 122, 123, 124 read the demultiplexed bitstream data stored in the bitstream buffer 222 of the buffer memory 22 for decoding via the memory interface 23. As such, the buffer memory 22 in the conventional system 2 of FIG. 2 must provide a large bandwidth for channel decoding and source decoding, thereby resulting in relatively high costs and power consumption.